Optical apparatus

ABSTRACT

An optical apparatus having a grip for gripping a camera body. The apparatus includes a lens element, a lens barrel configured to retain the lens element, a focus detection sensor disposed on an outer peripheral portion of the lens barrel, and a ring-shaped operation member configured to manually adjust at least focusing or zooming. The focus detection sensor is disposed on an outside of the ring-shaped operation member and on a same side as the grip of the camera body with respect to an optical axis of the lens element.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical apparatus such as a digitalcamera, a video camera, a digital still camera, a television camera, andan interchangeable lens including a focus detection sensor forautomatically focusing on an object.

2. Description of the Related Art

With a television auto focusing (TVAF) function in a video camera and atelevision camera, a video signal from an image sensor such as acharge-coupled device (CCD) is captured while a focusing lens is movedin a small amount to determine a focusing direction according to thedifference in contrast values obtained before and after moving thefocusing lens.

In such a TVAF system, when a focusing lens is disposed at a positionclose to an in-focus position, the focusing lens can immediately enteran in-focus state. However, in the case where the degree of blurring ishigh, it is necessary for a user to determine an in-focus position onlyafter moving the focusing lens up to an end of a focusing lens movablerange. Thus, the video image becomes unsightly for the user.

Thus, in a significantly defocused state, the contrast is very low, anda user cannot determine a focusing direction. Accordingly, in this case,it is necessary for a user to move the focusing lens to an infinitelydistant end or a closest end to look for a position at which a contrastsignal of a level is higher than a predetermined level. During thisoperation, the user is required to watch unfocused images, which causesthe user to feel uncomfortable.

Meanwhile, a digital still camera employs a passive focus detectionsensor as an auto focusing mechanism. A passive focus detection sensorcan detect the difference between two images separated by a separatorlens, and compute a focusing direction and an amount of unfocus, toimmediately obtain an in-focus state. In recent years, a focus detectionsensor is formed as a general-purpose module. Thus, a digital stillcamera has been downsized, the cost of manufacturing a digital stillcamera has been lowered, and the performance of a digital camera hasbeen more stabilized.

A hybrid video camera has been marketed which uses the TVAF function fornormal auto focusing and an inexpensive separate focus detection sensormodule for moving a focusing lens to an in-focus position at a highspeed in the case where the degree of blurring is high.

In a method discussed in Japanese Patent Application Laid-Open No.08-146287, a focus detection sensor module is disposed inside a lenshood so as to eliminate parallax between an optical element and arange-finding area of the focus detection sensor.

In a conventional method, it is difficult to mount a lens hood on anoptical apparatus with high accuracy because a focus detection sensormodule is disposed inside a lens hood. Thus, it is difficult to align arange-finding area with a shooting area with high accuracy. Furthermore,it is necessary to provide an electrical contact between a focusdetection sensor and a lens barrel in order to detach a focus detectionsensor module together with a lens hood. Thus, in a conventional method,the configuration of the apparatus becomes complicated and it isdifficult to stably perform an auto focus (AF) function.

SUMMARY OF THE INVENTION

The present invention is directed to an optical apparatus including afocus detection sensor, having a more stabilized configuration, and canimplement auto focusing with high accuracy without interfering with auser handling an operation ring.

According to an aspect of the present invention, an optical apparatushaving a grip configured to grip a camera body includes a lens element,a lens barrel configured to retain the lens element, a focus detectionsensor disposed on an outer peripheral portion of the lens barrel, and aring-shaped operation member configured to manually adjust at leastfocusing or zooming. The focus detection sensor is disposed on anoutside of the ring-shaped operation member and on a same side as thegrip of the camera body with respect to an optical axis of the lenselement.

Further features and aspects of the present invention will becomeapparent from the following detailed description of exemplaryembodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate exemplary embodiments, features,and aspects of the invention and, together with the description, serveto explain the principle of the invention.

FIG. 1 illustrates a video camera that is an optical apparatus accordingto an exemplary embodiment of the present invention.

FIG. 2 is a cross section of the optical apparatus in a verticaldirection according to the exemplary embodiment of the presentinvention.

FIG. 3 is an exploded perspective view illustrating a mechanism forretaining a focus detection sensor according to the exemplary embodimentof the present invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Various exemplary embodiments, features, and aspects of the presentinvention will now herein be described in detail with reference to thedrawings. It is to be noted that the relative arrangement of thecomponents, the numerical expressions, and numerical values set forth inthese embodiments are not intended to limit the scope of the presentinvention unless it is specifically stated otherwise.

Now, an exemplary embodiment of the present invention will be describedbelow. FIG. 1 illustrates a configuration of a video camera that is anoptical apparatus according to the present exemplary embodiment.Referring to FIG. 1, the video camera according to the present exemplaryembodiment includes a camera body 1, a viewfinder 2, and a grip 3. Theviewfinder 2 is disposed in an upper rear portion of the camera body 1.The grip 3 is disposed in a right portion of the camera body 1 from theviewfinder 2 so that a user can stably grip the camera body 1.

Furthermore, the video camera includes a lens barrel 4 for shooting. Thelens barrel 4 is fixedly mounted on the camera body 1. The lens barrel 4includes an optical element. A lens hood 5 is mounted on a front endportion of the lens barrel 4.

A focus detection sensor 6 is fixedly mounted on the lens barrel 4 on anouter peripheral portion, to an outside of a ring-shaped operationmember 7. The focus detection sensor 6 is mounted in a same direction asthe grip 3 from the optical axis. The focus detection sensor 6 isdisposed at a position distant from the user's left hand with which theuser mainly operates the lens barrel 4 and the camera body 1.

As described above, the focus detection sensor 6 is disposed at aposition and in a direction that do not interfere with a user operatingthe ring-shaped operation member 7 and the switches provided on the grip3.

FIG. 2 is a cross section of the lens barrel 4 in a vertical direction.FIG. 3 is an exploded perspective view illustrating a mechanism forretaining the focus detection sensor 6.

A stationary positive lens 11, which is a first lens unit, is fixedlymounted in a front stationary tube 12. A negative lens 13, which is asecond lens unit for performing variation, is retained in a second lensbarrel 14.

The second lens barrel 14 is driven by a motor (not shown) and can movealong the optical axis during zooming.

A fixed positive lens 15, which is a third lens unit, is retained in athird lens barrel 16. The third lens barrel 16 is retained on a rearstationary tube 17.

A positive lens 18, which is a fourth lens unit, is retained in a fourthlens barrel 19. The fourth lens unit (positive lens) 18 is driven by amotor (not shown) so as to move along the optical axis and performfocusing.

A diaphragm unit 20 can be fixedly mounted on the rear stationary tube17 with a screw. An image sensor (not shown) such as a CCD is mounted atthe back of the rear stationary tube 17 so as to capture a video signal.Furthermore, a seat 4 a for mounting the entire lens barrel 4 on thecamera body 1 is provided on an outer peripheral of the rear stationarytube 17.

An outer stationary tube 21 is fixedly mounted on an outer periphery ofthe front stationary tube 12. A manual focus (MF) ring 22 is disposed atthe front of the outer stationary tube 21. The MF ring 22 is pinched byan MF ring pressing ring 23, which is fixedly mounted on the outerstationary tube 21. The MF ring 22 is rotatably retained at a fixedposition.

An encoder 24 engages with a gear 23 a, which is disposed on an innerperiphery of the MF ring 22. Thus, a rotation angle of the MF ring 22can be detected as a pulse signal.

A manual zoom (MZ) ring 25 for performing manual zooming is disposed ina rear portion of the outer stationary tube 21. The MZ ring 25 ispinched by an MZ ring pressing ring 26. The MZ ring pressing ring 26 isfixedly mounted on the outer stationary tube 21. The MZ ring 25 isrotatably retained at a fixed position.

An encoder 27, which is similar to the encoder 24, engages with a gear25 a. The gear 25 a is disposed on an inner periphery of the MZ ring 25.Thus, a rotation angle of the MZ ring 25 can be detected as a pulsesignal.

Furthermore, a diaphragm ring 28 for manually adjusting a diaphragm isdisposed at the back of the MZ ring pressing ring 26. The diaphragm ring28 is rotatably retained by a diaphragm ring pressing ring 29 at a fixedposition. Pits and projections 28 a are formed in a shape like combteeth on the diaphragm ring 28. An interrupter (not shown) detects thepits and projections 28 a to detect a rotation angle of the diaphragmring 28.

The encoders 24 and 27 and the interrupter are wired to each other by aflexible printed circuit board (not shown) and are electricallyconnected to a control circuit (not shown) installed in the camera body1.

A sensor retaining base 31 is disposed so as to cover one portion of theMF ring 22. The sensor retaining base 31 can be fixed on the MF ringpressing ring 23 and the outer stationary tube 21 with a screw 31 a toretain the focus detection sensor 6.

The focus detection sensor 6 includes a separator lens for separating animage into two portions, a line sensor for detecting the contrast, and apassive focus detection sensor unit on which a signal processing circuitis integrally provided.

The focus detection sensor 6 is retained inside a concave portion 31 bof the sensor retaining base 31. Tilting of the focus detection sensor 6is adjusted with a dedicated tool so as to align the position of therange-finding area of the focus detection sensor with the shooting areaof the lens. The focus detection sensor 6 is fixed with an ultraviolet(UV) curable adhesive.

Since the lens according to the present exemplary embodiment is a zoomlens, adjustment is performed so that the range-finding area of thefocus detection sensor 6 reaches its center at a specific objectdistance in a shooting area at a telephoto end. The object distance isset so that the range-finding area does not go out of a target image, ina shootable range from a closest object to an infinitely-distant object.

When an optical element having a long focal length is used, the shootingarea becomes small. Accordingly, high accuracy is required in mountingthe focus detection sensor 6. Thus, it is a requisite to adjust andmount the focus detection sensor 6 with high accuracy. Accordingly, thefocus detection sensor 6 is mounted at a position close to the opticalelement.

A flexible printed circuit board 32 transmits a signal from the focusdetection sensor 6. The flexible printed circuit board 32 iselectrically connected to a flexible printed circuit board 33 via aconnector 33 a. The flexible printed circuit board 33 protrudes from thelens barrel 4. An auto focus (AF) signal is transmitted from a contactpoint 33 b to the control circuit provided within the camera body 1. Thecontact point 33 b extends to the rear portion of the lens barrel 4.

A sensor cover 34 covers the focus detection sensor 6. An apertureportion 34 a having a cover glass 35 is provided at the front of thesensor cover 34. The cover glass 35 allows light to be incident into thefocus detection sensor 6. The sensor cover 34 can be fixedly mounted onthe sensor retaining base 31 with a screw 34 b.

The lens hood 5, which is detachably mounted on the lens barrel 4 at thefront portion of the lens barrel 4, is detachably fixed to a front ring36 by a bayonet method. The front ring 36 can be fixed on the MF ringpressing ring 23 with a screw 23 b. The focus detection sensor 6 isdisposed at a position closer to the optical axis of the optical elementthan the outer periphery of the lens hood 5.

An aperture 5 a is provided in the back of the lens hood 5 so that theaperture 5 a does not interfere with a light flux L that is incident onthe focus detection sensor 6. Thus, the focus detection sensor 6 can bedisposed at a position close to the optical axis of the optical element.Accordingly, parallax between a target image and a range-findingposition of the focus detection sensor 6 can be reduced.

The video camera according to the present exemplary embodiment performsTVAF according to a contrast signal from the image sensor.

In TVAF performed by a conventional video camera, a focusing lens ismicro-vibrated by wobbling to detect the level of a contrast signal, andthus a moving direction of the focusing lens is determined to performfocusing. Accordingly, in a significantly unfocused state, theabove-described problem can arise.

The focus detection sensor 6 according to the present exemplaryembodiment is provided to prevent such a problem as an auxiliary means.With the passive type focus detection sensor 6, the focusing directionand the amount of shifting can be instantly computed even in the casewhere the degree of unfocus is very large. Accordingly, the focusinglens can be moved to an in-focus position at a high speed.

Thus, using the focus detection sensor 6, the focusing lens can be movedto a position close to the in-focus position at a high speed, and ahighly accurate in-focus state can be maintained by the TVAF performedaccording to an image signal. Accordingly, auto focusing can beperformed at a high speed. Thus, a user does not feel uncomfortable inshooting an image with the video camera according to the presentexemplary embodiment.

As described above, the focus detection sensor 6 is disposed at aposition close to the optical element on the same side as the cameragrip 3 on the outer periphery of the lens barrel 4. Accordingly, therange-finding area of the focus detection sensor 6 and a target imagecan be aligned with high accuracy. In addition, the user operatingmanual adjustment rings (the MF ring 22, the MZ ring 25, and thediaphragm ring 28) cannot be interfered with when focusing is manuallyadjusted.

Furthermore, in the present exemplary embodiment, the aperture 5 a forthe focus detection sensor 6 is provided in the lens hood 5.Accordingly, the focus detection sensor 6 can be disposed at a positionclose to the optical axis of the optical element. Thus, the amount ofparallax can be reduced.

In the optical apparatus according to the present exemplary embodiment,the focus detection sensor 6 is disposed on the same side as the grip 3.Accordingly, interference with a user operation from a protrudingportion of the focus detection sensor 6 can be prevented when the useroperates the manual adjustment ring to perform focusing and zooming.

In addition, the focus detection sensor 6 is not inside the lens hood 5but directly fixed on the lens barrel 4. Accordingly, the range-findingarea and a target image can be aligned with good accuracy. Thus, autofocusing can be performed with high accuracy.

Furthermore, the distance between the focus detection sensor 6 and theoptical element can be shortened. Accordingly, parallax in therange-finding area of a target image can be reduced.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all modifications, equivalent structures, and functions.

This application claims priority from Japanese Patent Application No.2006-214506 filed Aug. 7, 2006, which is hereby incorporated byreference herein in its entirety.

1. An optical apparatus having a grip configured to grip a camera body,the optical apparatus comprising: a lens element; a lens barrelconfigured to retain the lens element; a focus detection sensor disposedon an outer peripheral portion of the lens barrel; and a ring-shapedoperation member configured to manually adjust at least focusing orzooming, wherein the focus detection sensor is disposed on an outside ofthe ring-shaped operation member and on a same side as the grip of thecamera body with respect to an optical axis of the lens element.
 2. Theoptical apparatus according to claim 1, wherein the ring-shapedoperation member includes a manual focusing operation ring.
 3. Theoptical apparatus according to claim 1, wherein the focus detectionsensor includes a passive type sensor.
 4. The optical apparatusaccording to claim 1, further comprising a lens hood fixed on a frontend of the lens barrel, wherein the focus detection sensor is disposedcloser to the optical axis of the lens element than the outer peripheryof the lens hood, and wherein the lens hood has an aperture throughwhich a light flux can pass that is incident into the focus detectionsensor.
 5. The optical apparatus according to claim 4, wherein the lenshood can be detached from the lens barrel.
 6. An optical apparatuscomprising: a lens element; a lens barrel configured to retain the lenselement; a focus detection sensor disposed on an outer peripheralportion of the lens barrel; and a lens hood fixed on a front end of thelens barrel, wherein the focus detection sensor is disposed closer tothe lens element than an outer periphery of the lens hood, and whereinthe lens hood has an aperture through which a light flux can pass thatis incident into the focus detection sensor.
 7. The optical apparatusaccording to claim 6, wherein the focus detection sensor includes apassive type sensor.
 8. The optical apparatus according to claim 6,wherein the lens hood can be detached from the lens barrel.